/*
 * Copyright 2013-2019 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.wayne.gateway.filters.gateway;

import org.springframework.cloud.gateway.filter.GatewayFilter;
import org.springframework.cloud.gateway.filter.GatewayFilterChain;
import org.springframework.cloud.gateway.filter.factory.AbstractNameValueGatewayFilterFactory;
import org.springframework.cloud.gateway.support.ServerWebExchangeUtils;
import org.springframework.http.HttpHeaders;
import org.springframework.web.server.ServerWebExchange;
import reactor.core.publisher.Mono;

import static org.springframework.cloud.gateway.support.GatewayToStringStyler.filterToStringCreator;

/**
 * @author Spencer Gibb
 */
public class WayneSetResponseHeaderGatewayFilterFactory
        extends AbstractNameValueGatewayFilterFactory {

    @Override
    public GatewayFilter apply(NameValueConfig config) {
        return new GatewayFilter() {
            @Override
            public Mono<Void> filter(ServerWebExchange exchange,
                                     GatewayFilterChain chain) {
                String value = ServerWebExchangeUtils.expand(exchange, config.getValue());
                return chain.filter(exchange).then(Mono.fromRunnable(() -> {
                    HttpHeaders headers = exchange
                            .getResponse().getHeaders();
                    headers = HttpHeaders.writableHttpHeaders(headers);
                    headers.set(config.getName(), value);
                }));
            }

            @Override
            public String toString() {
                return filterToStringCreator(WayneSetResponseHeaderGatewayFilterFactory.this)
                        .append(config.getName(), config.getValue()).toString();
            }
        };
    }

}
